It is the long term goal of this research to characterize all the significant transport mechanisms in corneal epithelium and endothelium which both produce electric current and contribute to fluid transport by these cells and to determine the specific role of these transporters in corneal deturgescence and in the maintenance of corneal transparency. Six specific aims are proposed: 1) Measure the currents produced by the sodium pump, the sodium-bicarbonate cotransporter, the sodium-calcium exchanger, and the sodium-alanine transporter in single isolated cells of corneal epithelium and endothelium. 2) Study the bicarbonate stimulation of the potassium selective channel from rabbit corneal endothelial. 3) Characterize the properties of individual ion channels in corneal endothelium and corneal epithelium. 4) Utilize patch clamp techniques to measure electrical properties of endothelial cells in whole corneas and in the isolated descemet's- endothelial monolayer. 5) Determine the effect of culture on selected transporters in cornea epithelium and endothelium. 6) Study the properties and gating control of gap junctions between corneal epithelium and corneal endothelium. Patch clamp techniques will be used to characterize the detailed properties of single K+, cation, and anion channels in these cells. Three different techniques will be used to measure whole currents and mechanisms for controlling these currents will be investigated. Optical techniques with and without specific fluorescent probes will be used to measure cell volume and its control in corneal epithelium and endothelium and to measure Na+, K+, Ca++, and pH in these cells. Both optical and electrophysiological techniques will be used to measure gap junction properties and the control of connexon permeability.